The current trend in medicine is to perform less invasive procedures so as to minimize the trauma to the patient and shorten the recovery period. A major emphasis is to make as few incisions and as small of an incision as is possible to gain access to the interior of the patient. One area of medicine in which these techniques are being used more frequently is in heart surgery. Open heart surgery typically requires significant hospitalization and recuperation time for the open heart surgery to perform various surgical procedures such as coronary artery bypass grafting (CABG) is highly traumatic to the patient. In addition, open heart procedures require the use of cardiopulmonary bypass (CPB) which continues to represent a major assault on a host of body systems.
The CABG procedure generally involves open chest surgical techniques to patient is cut in order to spread the chest apart and provide access to the heart. During surgery the heart is stopped, and by the use of CPB blood is diverted from the lungs to an artificial oxygenator. In general, a source of arterial blood is then connected to a coronary artery downstream from the occlusion. The source of blood is often an internal artery, and the target coronary artery is typically among the anterior or posterior arteries which may be narrowed or occluded.
Multiple incisions have to be made in the arteries to accomplish the diversion of the blood. The leading cause of morbidity and disability following cardiac surgery is cerebral complications. At each incision, there is a risk of gaseous and solid micro and macro emboli, and less often perioperative cerebral hypoperfusion, which produce neurologic effects ranging from subtle neuropsychologic deficits to fatal stroke. Therefore, there is a need to minimize the number and size of incisions.
Open heart surgery is just one area of medicine, that would benefit from less invasive apparatus and procedures, others include dialysis and laparoscopic surgery just to name a couple.
Two obstacles to performing surgery is the number of incisions that must be made in various arteries, vessels, ventricles, atriums and cavity walls of the patient and the safe insertion and withdrawal of various devices and elements through those incisions.
One application for cannulas involves the augmenting or supplementation of pulmonary blood flow through the beating heart during heart surgery by use of one or more cannulas involved in the intake and return of blood into the circulatory system. The cannulas interface between the patient's circulatory system and the mechanical pumps that power the argumentation procedure.
When performing cardiac surgery cannulas are placed within the patient's blood stream and used for inflow and outflow of blood or other fluids. One such bypass circuit would be a cardiopulmonary bypass circuit (CPB), in which an outflow cannula is placed in the patient's right atrium and a return cannula is placed in the aorta. The outflow cannula can be further connected to an oxygenator, blood filter, or blood heater. Even though there are negative side effects of using on pump bypasses, doctors continue to do so because of the ease and reliability of establishing the circuit.
Though presently there is a movement away from stopped heart CPB to beating heart surgery. The movement to beating heart surgery is hampered by common bypass techniques and equipment. One such problem occurs while performing a coronary artery bypass graft (CABG) on the back side of the heart. In order to access vessels on the back side of the heart the surgeon must rotate the heart. Though rotating the heart while the heart is still beating raises new complications that were not present during stopped heart surgery. Many times rotating the beating heart leads to further complications such as a decrease in pulmonary pressure which results in a decrease in oxygen content in the patient's blood. Thus many times when a surgeon is performing a graft on the back side of the heart, the heart must be rotated and replaced many times to stabilize the patient's blood pressure.